In a conventional apparatus shown in FIG. 22, an output shaft C4 of an electric motor A1 serving as a drive source is connected to an input side of a driven unit A2 such as a fluid machinery via a joint A22 and an output shaft C7. In this case, transmission of a rotational power from the electric motor A1 is limited to a range in which the joint A22 can transmit the rotational power.
At the same time, there is a need to transmit a rotational power beyond the range in which the joint A22 can transmit the rotational power.
In order to meet such a need, as shown in FIGS. 23A and 23B, there has been proposed a transmission apparatus A15 which distributes or divides a rotational power that is input from a drive source A1.
According to the transmission apparatus A15 shown in FIGS. 23A and 23B, the rotational power from the drive source A1 is distributed to a power line R1 and a power line R2 by a dividing unit 6, so that the rotational power below the transmission limit of a continuously variable transmission A 20 is distributed to the power line R1 and the residual rotational power is distributed to the power line R2.
The rotational powers divided by the dividing unit 6 are converged by a differential planetary gear unit A30 disposed at an output side of the continuously variable transmission A20, so that the converged rotational power is transmitted to a driven unit A2 via a single output shaft 37.
With this structure, the rotational power beyond the transmission limit of the continuously variable transmission A20 can be transmitted to the driven side.
However, the continuously variable transmission A20 shown in FIGS. 23A and 23B employs a mechanism of a toroidal-type continuously variable transmission (CVT). Since the toroidal-type CVT is of a contact type, there are limits to a maximum transmission power and a service life. Therefore, it is difficult to apply the toroidal-type CVT to a large equipment which is required to transmit a large power, and to an industrial machinery which is required to have a reliability.
Further, various kinds of vibrations and impacts, such as pulsation due to power fluctuation, shock vibration at speed change, and torsion vibration of the output shaft, are transmitted or occur to an output side of the toroidal-type CVT. Accordingly, the toroidal-type CVT, which utilizes solid friction, is problematic in output fluctuation and durability because of such vibrations and impacts.
In addition, another type of conventional transmission apparatus has the same problems.